Effect of a Thickening Agent on the Rheology of 3D Printed Gels from Red Seaweed Extracts

Seaweeds are valued for the polysaccharides they contain, like agar, carrageenan, or alginate, which are commonly used to improve food textures. This study focused on the printability of three red seaweed species – Chondrus crispus, Gelidium Corneum and Gracilaria gracilis – known for their natural gelling properties. Traditional extraction methods involve harsh chemicals and time-consuming processes. Thus, to address sustainability and safety concerns, a water-based extraction method was used aiming to produce eco-friendly food gels from the extracts. The main goal was to analyze gelation during 3D printing and assess the effectiveness of the extraction method. A comprehensive rheological protocol, including different Small Amplitude Oscillatory Shear (SAOS) tests (i.e., cooling ramps, time sweeps, frequency sweeps), was employed. The study explored two key printing parameters: the addition of locust bean gum (LBG) as a thickener, and the printing temperature. Results revealed a different behavior depending on the seaweed species. Therefore, gels from G. corneum and G. gracilis initially showed an initial weaker viscoelastic behaviour compared to C. crispus, but when LBG concentration was increased gel definition improved substantially. In contrast, C. crispus gels remained stable and were less affected by the parameters studied.